1. Field of the Invention
This invention relates to polyester polycarbonates, their preparation and use in making polymer foams including both polyurethane polymers and polyisocyanurate polymers.
2. Description of the Prior Art
Polyurethane polymers and polyisocyanurate polymers such as those in rigid and flexible foam form are well known in the art. The latter type of polymers are made by utilizing a polyisocyanurate group formation catalyst to promote formation of both isocyanurate linkages and urethane linkages to produce urethane-modified polyisocyanurate polymers.
Both polyesters and polycarbonates have been used in the preparation of polyurethane polymers such as those in foam form. Materials of this type are used to prepare both polyurethane and polyisocyanurate flexible and rigid foams as well as semi-flexible and semi-rigid foam types. See, for example, U.S. Pat. Nos. 2,915,550; 3,133,113; 3,248,415; 3,248,414; 3,248,416; 3,764,457; and 3,699,679.
However, many prior art foams prepared from polyol sources of these types are deficient in a number of sought-after properties. For example, many polyisocyanurate rigid foams so prepared do not have a sufficiently low friability to be commercially useful. In other instances the foams do not have the proper degree of burn resistance. In yet other instances the foam formulations are not sufficiently viscous. Thus, when such urethane systems are applied in spray form the relatively low viscosity products tend to sag when applied.
It therefore would be a distinct improvement in the art to prepare novel polyester polycarbonates useful in making polyurethane and polyisocyanurate foams which do not possess the above-discussed drawbacks and others. Other objects will appear hereinafter.